A 30-month study of drip hydrochemistry from Kooringa Cave, eastern Australia, revealed a clear geochemical response to the 2002–2003 El Niño. Through the drought, drip discharge fell to base flow, drip Ca²⁺ concentrations fell by half and drip Mg/Ca and Sr/Ca increased in a co-varying pattern. Calcite Mg/Ca and Sr/Ca predicted from drip waters displayed a marked increase through, and just beyond, the period of greatest moisture deficit. The results suggest that stalagmites from shallow caves in drought-sensitive eastern Australia potentially preserve a valuable record of El Niño-La Niña history.